Device for polishing optical disk

ABSTRACT

The present invention relates to a polishing apparatus for restoring an optical disk. The objects of the present invention are as follows: to obtain an equal pressure appropriately required for polishing; to correct the accuracy of parallelism between the rotation planes of an optical disk and a polishing sheet; to remove roundness formed on the outer edge of an optical disk and unevenness in polishing; and to prevent clogging of the surface of a polishing sheet by the active elimination of abrasive filings and an occurrence of scratches on the surface of an optical disk due to the clogging. For the purpose of achieving the above objects, in an apparatus for polishing an optical disk composed of a disk rotator A and a polishing mechanism B, the polishing mechanism B has an elastic mechanism D for elastically holding a polishing pad C, a polishing sheet of the polishing pad C has such an elasticity that the deformation amount Δx is 0.005 mm to 0.3 mm when the polishing sheet contacts the surface of the optical disk with a pressure required for polishing, the elastic mechanism D is constructed to have elasticity in the direction perpendicular to the rotation plane of the optical disk and rigidity in the direction parallel to the rotation plane of the optical disk, and the ratio of the disk angular speed ωa of the disk rotator A to the polishing sheet angular speed ωb of the polishing mechanism B is regulated to satisfy the range of 0.2&lt;ωa/ωb&lt;1.5.

TECHNICAL FIELD

[0001] The present invention relates to a polishing apparatus forrestoring optical disks, such as CD, DVD, VD and LD.

BACKGROUND ART

[0002] Recently, optical disks have been selling in large quantities.When a flaw or flaws are made on its surface, it is sometimes impossibleto read data from the disk. It is therefore desirable to repair the diskand restore it to a readable state. In view of resource saving, it isnot desirable to dispose of such reusable optical disks in largequantities.

[0003] Reference is made to FIG. 5, which shows an example of aconventional disk polishing apparatus. The apparatus is composed of adisk rotator A2 for rotating an object 31 and a polishing mechanism B2for polishing the surface of the object 31. In the polishing mechanismB2, a polishing pad C2 is attached to a rotating substrate 33 fixed to arotation shaft 32 via such an attachment means as “Velcro” (registeredtrademark). In the polishing pad C2, a polishing sheet 36 is attached tothe bottom of a spongy elastic body 35.

[0004] Reference is made to FIG. 6a, which shows the case of polishingthe surface of an optical disk with the above-constructed polishingapparatus. When the elastic body 35 of the polishing pad C2 is too soft,deformation occurs in the polishing face. Thus, in the course ofpolishing, roundness E is formed on the outer edge of the optical disk31.

[0005] When, on the other hand, the elastic body 35 of the polishing padC2 is not pliable, the pressure contact between the polishing face andthe surface of the optical disk is tightened in part. It is thereforedifficult to eliminate abrasive filings (e.g. polycarbonate powder),which clog the surface of the polishing sheet. Thus, the polishing powerdecreases and the accumulated filings cause small shallow cuts (i.e.scratches) on the surface of the optical disk.

[0006] Further, when the rotation plane of the optical disk is not keptparallel to that of the polishing sheet 36, it is impossible toadequately correct the planar accuracy of the polished face in thecourse of polishing, as shown in FIG. 6b.

[0007] Accordingly, the problems to be solved by the present inventionare as follows: (1) to obtain an appropriate pressure required forpolishing; (2) to correct the accuracy of parallelism between therotation planes of an optical disk and a polishing sheet; (3) to removeroundness formed on the outer edge of an optical disk and unevenness inpolishing; and (4) to prevent clogging of the surface of a polishingsheet by the active elimination of abrasive filings and an occurrence ofscratches on the surface of an optical disk due to the clogging.

DISCLOSURE OF THE INVENTION

[0008] The first objective of the present invention is to provide anapparatus for polishing an optical disk composed of a disk rotator A forrotating an optical disk and a polishing mechanism B for polishing thesurface of the optical disk, wherein the polishing mechanism B has anelastic mechanism D for elastically holding a polishing pad C and apolishing sheet of the polishing pad C has such an elasticity that thedeformation amount Δx is 0.005 mm to 0.3 mm when the polishing sheetcontacts the surface of the optical disk with a pressure required forpolishing.

[0009] In this invention, it is possible to prevent clogging of thesurface of the polishing sheet by the active elimination of abrasivefilings and an occurrence of scratches on the surface of the opticaldisk due to the clogging. It is also possible to remove roundness formedon the outer edge of the optical disk and unevenness in polishing byregulating elasticity of the polishing sheet.

[0010] The second objective of the present invention is to provide anapparatus for polishing an optical disk composed of a disk rotator A forrotating an optical disk and a polishing mechanism B for polishing thesurface of the optical disk, wherein the polishing mechanism B has anelastic mechanism D for elastically holding a polishing pad C and theelastic mechanism D is constructed to have elasticity in the directionperpendicular to the rotation plane of the optical disk and rigidity inthe direction parallel to the rotation plane of the optical disk.

[0011] In this invention, it is possible to correct the accuracy ofparallelism between the rotation planes of the optical disk and thepolishing sheet. Thereby, the pressure contact between the polishingface and the surface of the optical disk can be appropriately equalized.

[0012] Thus, it is possible to remove roundness formed on the outer edgeof the optical disk and unevenness in polishing.

[0013] The third objective of the present invention is to provide anapparatus for polishing an optical disk composed of a disk rotator A forrotating an optical disk and a polishing mechanism B for polishing thesurface of the optical disk, wherein the ratio of the disk angular speedωa of the disk rotator A to the polishing sheet angular speed cob of thepolishing mechanism B satisfies the range of 0.2<ωa/ωb<1.5.

[0014] In this invention, it is possible to increase the polishingefficiency and thus obtain an adequate amount of polishing by settingthe ratio of the disk angular speed of the disk rotator A and thepolishing sheet angular speed of the polishing mechanism B within apredetermined range. It is also possible to prevent an occurrence ofclogging by facilitating the elimination of filings. Further, enduranceof the polishing sheet can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a perspective view showing the configuration of the diskrotator and the polishing mechanism.

[0016]FIG. 2 is a side view of the polishing mechanism with a polishingpad attached.

[0017]FIG. 3 is a partial sectional view of the polishing mechanism witha polishing pad unattached.

[0018]FIG. 4a is a partial sectional view of another type of elasticmechanism.

[0019]FIG. 4b is a plan view of the elastic mechanism shown in FIG. 4a.

[0020]FIG. 5 is a side view showing the configuration of theconventional disk rotator and polishing mechanism.

[0021]FIG. 6a is a partial sectional view explaining the function of theconventional polishing mechanism.

[0022]FIG. 6b is a partial sectional view explaining the function of theconventional polishing mechanism.

[0023]FIG. 7a is a plan view of a disk of a sample 1 in experimentexample 2 and a perspective view of traces of polishing.

[0024]FIG. 7b is a plan view of a disk of a sample 7 in experimentexample 2.

[0025]FIG. 7c is a plan view of a disk of a sample 4 in experimentexample 2 and a perspective view of traces of polishing.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] An embodiment of the present invention is described according tothe drawings. A wet polishing apparatus is used in the presentembodiment. In the wet polishing apparatus, when the surface 2 a of apolishing sheet of a polishing pad C is pressed into contact with thesurface 1 a of an optical disk for the purpose of polishing, such liquidas water is supplied to the interface between the surfaces 1 a and 2 a.Thereby, frictional heat is eased and the elimination of filings isattained in the course of polishing.

[0027] Reference is made to FIGS. 1 and 2, which show an apparatus forpolishing an optical disk according to the present embodiment. Theapparatus is composed of a disk rotator A for rotating an optical disk 1and a polishing mechanism B for polishing the surface of the opticaldisk. The polishing mechanism B has an elastic mechanism D forelastically holding a polishing pad C.

[0028] In the disk rotator A, the optical disk 1 is mounted on arotating substrate 4 coupled with a rotation shaft 3.

[0029] In the polishing mechanism B, the elastic mechanism D isconstructed so that a second rigid body 7 is connected to a first rigidbody 6 in a floating state, as shown in FIGS. 2 and 3. The polishing padC is attached to the second rigid body 7. In the second rigid body 7,plural shafts 7 a project upward from its circumferential vicinity. Thefirst rigid body 6 is coupled with a rotation shaft 5. In the firstrigid body 6, plural shaft holes 6 a are provided in its circumferentialvicinity. The shaft 7 a is fitted into the shaft hole 6 a through a coilspring 8 between rigid bodies 6 and 7. The shaft 7 a is capable ofsliding and is fixed by a fixing member 9.

[0030] The elastic mechanism D is therefore constructed to haveelasticity in the direction perpendicular to the rotation plane of theoptical disk 1 and rigidity in the direction parallel to the rotationplane of the optical disk 1. A magnetic body 10 is provided on thebottom of the second rigid body 7. The magnetic body 10 is magneticallyjoined with a metal substrate 11 of the polishing pad C as describedlater.

[0031] In the polishing pad C, as shown in FIG. 3, a polishing sheet 2is attached via an elastic sheet 12 to the metal substrate 11 joinedwith the magnetic body 10.

[0032] The polishing pad C can be attached to the second rigid body 7 bya Hook-and-Loop fastener, such as “Velcro” (registered trademark), inaddition to the magnetic attachment/detachment means. Instead of thepolishing pad C being attached to and detached from the second rigidbody 7, the integrated elastic mechanism D and polishing pad C may beattached to and detached from the rotation shaft 5.

[0033] Reference is made to FIGS. 4a and 4 b, which show another type ofthe elastic mechanism D. In this type elastic mechanism D, a magneticbody 20 is attached via a ring 29 to a ribbed elastic body 28 fixed to arotation shaft 25 of a polishing mechanism B1. As shown in FIG. 4b(which is a plan view of the elastic mechanism shown in FIG. 4a), theribbed elastic body 28 is formed so that an inner part 28 a is connectedto an outer part 28 b by ribs 28 d while creating a space 28 c. Theelastic mechanism D1 is thus constructed. Therefore, the elasticmechanism D1 is also constructed to have elasticity in the directionperpendicular to the rotation plane of the optical disk and rigidity inthe direction parallel to the rotation plane of the optical disk.

EXPERIMENT EXAMPLE 1

[0034] The polishing pads were prepared by using the elastic sheets thatdiffered in material and thickness. Next, these polishing pads wereattached to the polishing mechanism B of the polishing apparatusaccording to the present embodiment. The surface of the polishing sheetof each polishing pad was pressed into contact with the surface of theoptical disk with a pressure required for polishing. Samples 1-6 werethus obtained. Reference is made to Table 1, which shows the deformationamount Ax of the surface of the polishing sheet in this case. Table 1also shows the comprehensive as well as the individual rating regardingclogging of the surface of the polishing sheet and roundness formed onthe outer edge of the optical disk. In the present experiment, therotation speed of the disk rotator A is 500 rpm and that of thepolishing mechanism B is 1200 rpm. The disk rotator A and the polishingmechanism B rotate in the same direction.

[0035] In the sample 1, the polishing sheet is directly attached to themetal substrate 11 of the polishing pad. That is, the elastic sheet isnot in use. In the samples 2-6, various kinds of synthetic rubber areused as the elastic sheet. Also, the elastic sheets differ in thickness.TABLE 1 Material of Deformation Compre- Sample Polishing Amount ΔxRating of Rating of hensive No. Sheet (mm) Clogging Roundness Rating 1 —0.000 X ◯ X 2 Synthetic 0.005 Δ ◯ Δ Rubber 3 Synthetic 0.01 ◯ ◯ ◯ Rubber4 Synthetic 0.1 ◯ ◯ ◯ Rubber 5 Synthetic 0.3 ◯ Δ Δ Rubber 6 Synthetic0.5 ◯ X X Rubber

[0036] Based on this result, the following facts were found: when thedeformation amount (depression amount) Δx is small, the surface of thepolishing sheet is likely to be clogged; when it is large, roundness islikely to be formed on the outer edge of the optical disk; and it ispreferable to set the deformation amount (depression amount) Ax withinthe range of 0.005 mm to 0.3 mm, more preferably within the range of0.01 mm to 0.1 mm.

EXPERIMENT EXAMPLE 2

[0037] With the polishing apparatus according to the present embodiment,the disk angular speed ωa of the disk rotator A and the polishing sheetangular speed ωb of the polishing were regulated to set the angularspeed ratio at the values shown in Table 2. Samples 1-7 were thusobtained. As for these samples, an amount of polishing was measured. Inthe meantime, the elimination of filings, an occurrence of clogging,etc. were rated. These measurement and ratings are comprehensively shownin the column of “Rating of Amount of Polishing ” of Table 2. TABLE 2Disk Angular Speed/ Polishing Sheet Rating of Sample Angular SpeedAmount of No. (ωa/ωb) Polishing 1 0.1 X 2 0.2 Δ 3 0.4 ◯ 4 0.6 ⊚ 5 1.0 ◯6 1.5 Δ 7 2.0 X

[0038] As for the sample No. 1 (ratio of 0.1) where the disk angularspeed is low and the polishing sheet angular speed is high, thepolishing sheet always effects polishing in the direction La parallel toa trace of polishing Ka, as shown in FIG. 7a. In this case, while thesame abrasive grains of the polishing sheet always polish a peak part Yof the traces of polishing ka, the other ones always polish a valleypart T thereof. Therefore, the polishing efficiency is low and theamount of polishing decreases. Further, the polishing sheet is likely tobe clogged because it is difficult to eliminate the filings. Thereby,endurance of the polishing sheet decreases.

[0039] As for the sample No. 7 (ratio of 2.0) where the disk angularspeed is high and the polishing sheet angular speed is low,long-distance polishing is effected while an abrasive grain on thesurface of the polishing sheet rotates once, as shown in FIG. 7b. Theabrasive grain is therefore likely to have polishing heat. Consequently,when the softened filings stick to the surface of the abrasive grain(i.e. polycarbonate powder), frictional resistance increases due to theclogging and thereby the polishing efficiency decreases.

[0040] As for the sample No. 4 where the ratio of the disk angular speedand the polishing sheet angular speed is 0.6, the polishing sheeteffects polishing in the direction Lc nearly perpendicular to a trace ofpolishing Kc, as shown in FIG. 7c. Therefore, differently from the caseof the sample No. 1, the same part of the abrasive grains does notpolish the peak part Y. That is, the peak part Y and valley part T arepolished alternatively. In this case, the filings produced by polishingthe peak part T are actively eliminated through the valley part T andthereby an occurrence of clogging is prevented.

[0041] Based on the above result, the following facts were found: whileit is desired to set the ratio of the disk angular speed and thepolishing sheet angular speed appropriately, it is preferable to set theangular speed ratio within the range of 0.2<ωa/ωb<1.5, more preferablywithin the range of 0.4<ωa/ωb<1.0.

[0042] As described above, in this invention, it is possible to preventclogging of the surface of the polishing sheet by the active eliminationof abrasive filings and an occurrence of scratches on the surface of theoptical disk due to the clogging. It is also possible to correct theaccuracy of parallelism between the rotation planes of the optical diskand the polishing sheet. Thereby, the pressure contact between thepolishing face and the surface of the optical disk can be appropriatelyequalized. Thus, it is possible to remove roundness formed on the outeredge of the optical disk and unevenness in polishing. It is furtherpossible to increase polishing efficiency and thus obtain an adequateamount of polishing by setting the ratio of the disk angular speed ofthe disk rotator A and the polishing sheet angular speed of thepolishing mechanism B within a predetermined range. Furthermore, it ispossible to prevent an occurrence of clogging by facilitating theelimination of filings and thereby endurance of the polishing sheet canbe improved.

1. An apparatus for polishing an optical disk composed of a disk rotatorA for rotating an optical disk and a polishing mechanism B for polishingthe surface of the optical disk, wherein the polishing mechanism B hasan elastic mechanism D for elastically holding a polishing pad C and apolishing sheet of the polishing pad C has such an elasticity that thedeformation amount Δx is 0.005 mm to 0.3 mm when the polishing sheetcontacts the surface of the optical disk with a pressure required forpolishing.
 2. An apparatus for polishing an optical disk composed of adisk rotator A for rotating an optical disk and a polishing mechanism Bfor polishing the surface of the optical disk, wherein the polishingmechanism B has an elastic mechanism D for elastically holding apolishing pad C and the elastic mechanism D is constructed to haveelasticity in the direction perpendicular to the rotation plane of theoptical disk and rigidity in the direction parallel to the rotationplane of the optical disk.
 3. An apparatus for polishing an optical diskcomposed of a disk rotator A for rotating an optical disk and apolishing mechanism B for polishing the surface of the optical disk,wherein the ratio of the disk angular speed ωa of the disk rotator A tothe polishing sheet angular speed ωb of the polishing mechanism Bsatisfies the range of 0.2<ωa/ωb<1.5.
 4. The apparatus for polishing anoptical disk according to one of claims 1 to 3, wherein the elasticmechanism D includes: a) a first plate member; b) a second plate membersliding against a bar member provided on the first plate member; and c)an elastic member with the bar member fitted by insertion between thefirst and second plate members.
 5. The apparatus for polishing anoptical disk according to one of claims 1 to 3, wherein the elasticmechanism D is a ribbed elastic body.
 6. The apparatus for polishing anoptical disk according to one of claims 1 to 5, wherein the polishingpad is attached to and detached from the elastic mechanism D by amagnetic attachment/detachment means or a Hook-and-Loop fastener.
 7. Theapparatus for polishing an optical disk according to one of claims 1 to6, wherein the integrated elastic mechanism D and polishing pad C areattached to and detached from a rotation shaft.